let a = "123";
let b =  123;
console.log(b+Number(a));



function try1(a){
    if(a<0){
        return("负数");
    }else if(a==0){
       return("零");
    }else{
        return("正数");
    }
}
console.log(try1(4))


function sum(n){
    let sum=0;
    for(let i=1;i<=n;i++){
        if(i % 2===0){
         sum=sum+i;
           
        }
    }
    return sum;
}
console.log(sum(100));